Multiple-unit probe pusher and system for driving eddy current inspection probes in the heat exchanger tubes of a nuclear steam generator

Abstract

Disclosed is a system for driving inspection probes through steam generator tubes of a nuclear power plant, particularly eddy current probes. The system utilizes a single conduit that is connectable to the tube sheet of a steam generator and comprises a multiple-unit probe pusher having a housing containing a plurality of independently actuable drive paths, a multiple-unit probe storage device including a plurality of independently movable take-up reels, and a guide or deflector device for directing any one probe that is driven from any one of the drive paths of the probe pusher to the single conduit. Preferably, the entire system is also remotely controllable. The system enables one probe to be in use for tube inspection while providing readily available spare probes to replace a defective probe with a minimum of downtime and worker radiation exposure.

We claim: 
     
       1. A system for driving inspection probes through heat exchanger tubes in a nuclear steam generator, said system comprising: a) a multiple-unit probe pusher including a housing containing a plurality of independently actuable drive means and a same plurality of inlets and outlets passing through said housing, thereby providing a plurality of probe drive paths, each having an inlet, an outlet, and a drive means;   b) a control means for independently actuating each of said plurality of drive means of said multiple-unit probe pusher;   c) a multiple-unit probe storage means located outside of the nuclear steam generator including a plurality of probe take-up means for feeding and receiving a probe to and from said multiple-unit probe pusher, wherein there is at least one take-up means for each probe drive path; and   d) a guide means for receiving and directing selected probes from any one of said plurality of probe drive paths from said multiple-unit probe pusher to selected tubes for inspection,   wherein said guide means is incapable of receiving all of said probes simultaneously such that at least one of said probes and its associated drive path is immediately available as a spare in the event that one of the selected probes fails.   
     
     
       2. The system of claim 1, wherein said plurality of probe take-up means are each operable independently of each other. 
     
     
       3. The system of claim 2, wherein each probe take-up means comprises a reel rotatably mounted on a common axis. 
     
     
       4. The system of claim 2, wherein each probe take-up means comprises a reel rotatably mounted on a common axis, and each reel is independently driven by a motor means that is operatively connected with said control means so as to actuate one of said motor means concurrently with the associated drive means of each probe drive path. 
     
     
       5. The system of claim 2, including a drive shaft and at least two driven shafts rotatably mounted in said housing, wherein said driven shafts are positively driven from said drive shaft by transfer means, and each of said driven shafts is provided with drive rollers of a same number as there are drive paths, and rollers being selectively connected to said driven shafts by clutch means. 
     
     
       6. The system of claim 5, wherein said inlets and said outlets are colinearly provided through said housing and at least one driven shaft is disposed on each side of a plane passing through said inlets and said outlets. 
     
     
       7. The system of claim 6, wherein each of said plurality of drive means comprises one roller on each driven shaft that is positioned in line with the inlet and outlet of each drive path, thereby making a set of rollers for each drive path. 
     
     
       8. The system of claim 7, wherein said control means is electrically connected to each clutch means so that upon energization of the clutch means, the roller is drivingly engaged to said driven shaft, whereby each set of rollers can be concurrently engaged to the driven shafts independently of other sets of rollers to independently actuate each drive means of each probe drive path. 
     
     
       9. The system of claim 8, wherein there are four driven shafts with two on each side of said plane, and there are three rollers on each driven shaft corresponding to three drive paths. 
     
     
       10. The system of claim 9, wherein the driven shafts on one side of said plane are adjustably connected to said housing by bias means so that a nip between rollers of one set of rollers can be varied. 
     
     
       11. The system of claim 10, wherein said bias means comprises a swinging bracket pivotally mounted about an idler shaft, said swinging bracket rotatably supporting one driven shaft and its associated rollers, and an adjustable tension spring means between said swinging bracket and said housing. 
     
     
       12. The system of claim 11, wherein said transfer means includes a drive gear fixed with said drive shaft, an idler gear fixed with said idler shaft and in drive engagement with said drive gear, and driven gears fixed to each driven shaft with two driven gears in engagement with said idler gear and two driven gears in engagement with said drive gear. 
     
     
       13. The system of claim 12, wherein said drive shaft extends out of said housing and is driven by an external motor means, and said motor means is connected to said control means for selective actuation said motor means capable of driving said rollers at a speed sufficient to drive an inspection probe at its operational speed. 
     
     
       14. The system of claim 1, wherein said guide means is positioned adjacent said outlets of said multiple-unit probe pusher, said guide means comprising a funnel-like member having a first opening facing said outlets that is of sufficient size to receive a probe coming from of any one of the outlets, and deflector walls for directing any driven probe toward a second opening that is smaller than said first opening but sufficiently large to permit one probe to pass therethrough, said second opening being connected to said conduit. 
     
     
       15. The system of claim 1, wherein said guide means is positioned adjacent said outlets of said multiple-unit probe pusher, said guide means comprising a slider block with means for connection to said conduit, and slide means for movably positioning said conduit to receive a probe driven from any one of said outlets. 
     
     
       16. A system for driving eddy current inspection probes through heat exchanger tubes of a nuclear steam generator, said system comprising: a) a multiple-unit probe pusher including a housing containing a plurality of independently actuable drive means and a same plurality of inlets and outlets passing through said housing, thereby providing a plurality of probe drive paths, each comprising an inlet, an outlet and a drive means;   b) a control mans for independently actuating each of said plurality of drive means of said multiple-unit probe pusher;   c) a multiple-unit probe storage means located outside of the nuclear generator including a plurality of probe take-up means for feeding and receiving a probe to and from said multiple-unit probe pusher, wherein there is at least one take-up means for each probe drive path and each take-up means operates independently of the others; and   d) a guide means positioned adjacent the outlets of said multiple-unit probe pusher for receiving and directing only one of said probes from said multiple-unit probe pusher to a single tube for inspection such that the other probes and their associated drive paths are immediately available as spares in the event that the selected probe fails.   
     
     
       17. The system of claim 16, wherein each probe take-up means comprises a reel rotatably mounted on a common axis, and each reel is freely rotatable on said common axis. 
     
     
       18. The system of claim 16, wherein each probe take-up means comprises a reel rotatably mounted on a common axis, and each reel is independently driven by a motor means that is operatively connected with said control means so as to actuate one of said motor means concurrently with the associated drive means of each probe drive path. 
     
     
       19. The system of claim 16, including a drive shaft and at least two driven shafts rotatably mounted in said housing, wherein said driven shafts are positively driven from said drive shaft by transfer means, and each of said driven shafts is provided with drive rollers of a same number as there are drive paths, and rollers being selectively connected to said driven shafts by clutch means. 
     
     
       20. The system of claim 19, wherein said inlets and said outlets are colinearly provided through said housing and at least one driven shaft is disposed on each side of a plane passing through said inlets and said outlets. 
     
     
       21. The system of claim 20, wherein each of said plurality of drive means comprises one roller on each driven shaft that is positioned in line with the inlet and outlet of each drive path, thereby making a set of rollers for each drive path. 
     
     
       22. The system of claim 21, wherein said control means is electrically connected to each clutch means so that upon energization of the clutch means, the roller is drivingly engaged to said driven shaft, whereby each set of rollers can be concurrently engaged to the driven shafts independently of other sets of rollers to independently actuate each drive means of each probe drive path. 
     
     
       23. The system of claim 22, wherein there are four driven shafts with two on each side of said plane, and there are three rollers on each driven shaft corresponding to three drive paths. 
     
     
       24. The system of claim 23, wherein the driven shafts on one side of said plane are adjustably connected to said housing by bias means so that a nip between rollers of one set of rollers can be varied. 
     
     
       25. The system of claim 24, wherein said bias means comprises a swinging bracket pivotally mounted about an idler shaft, said swinging bracket rotatably supporting one driven shaft and its associated rollers, and an adjustable tension spring means between said swinging bracket and said housing. 
     
     
       26. The system of claim 25, wherein said transfer means includes a drive gear fixed with said drive shaft, an idler gear fixed with said idler shaft and in drive engagement with said drive gear, and driven gears fixed to each driven shaft with two driven gears in engagement with said idler gear and two driven gears in engagement with said drive gear. 
     
     
       27. The system of claim 26, wherein said drive shaft extends out of said housing and is driven by an external motor means, and said motor means is connected to said control means for selective actuation said motor means capable of driving said rollers at a speed sufficient to drive an inspection probe at its operational speed. 
     
     
       28. The system of claim 16, wherein said guide means is positioned adjacent said outlets of said multiple-unit probe pusher, said guide means comprising a funnel-like member having a first opening facing said outlets that is of sufficient size to receive a probe coming from of any one of the outlets, and deflector walls for directing any driven probe toward a second opening that is smaller than said first opening but sufficiently large to permit one probe to pass therethrough, said second opening being connected to said conduit. 
     
     
       29. The system of claim 16, wherein said guide means is positioned adjacent said outlets of said multiple-unit probe pusher, said guide means comprising a slider block with means for connection to said conduit, and slide means for movably positioning said conduit to receive a probe driven from any of said outlets.